Add support for tracking call counts and elapsed runtime for user-defined

functions.

Note that because this patch changes FmgrInfo, any external C functions
you might be testing with 8.4 will need to be recompiled.

Patch by Martin Pihlak, some editorialization by me (principally, removing
tracking of getrusage() numbers)

src/backend/utils/adt/pgstatfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.51 2008/05/12 00:00:51 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.52 2008/05/15 00:17:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -39,6 +39,10 @@ extern Datum pg_stat_get_last_autovacuum_time(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_last_analyze_time(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_last_autoanalyze_time(PG_FUNCTION_ARGS);
 
+extern Datum pg_stat_get_function_calls(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_function_time(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_function_self_time(PG_FUNCTION_ARGS);
+
 extern Datum pg_stat_get_backend_idset(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_activity(PG_FUNCTION_ARGS);
 extern Datum pg_backend_pid(PG_FUNCTION_ARGS);
@@ -325,6 +329,39 @@ pg_stat_get_last_autoanalyze_time(PG_FUNCTION_ARGS)
 		PG_RETURN_TIMESTAMPTZ(result);
 }
 
+Datum
+pg_stat_get_function_calls(PG_FUNCTION_ARGS)
+{
+	Oid	funcid = PG_GETARG_OID(0);
+	PgStat_StatFuncEntry *funcentry;
+
+	if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
+		PG_RETURN_NULL();
+	PG_RETURN_INT64(funcentry->f_numcalls);
+}
+
+Datum
+pg_stat_get_function_time(PG_FUNCTION_ARGS)
+{
+	Oid	funcid = PG_GETARG_OID(0);
+	PgStat_StatFuncEntry *funcentry;
+
+	if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
+		PG_RETURN_NULL();
+	PG_RETURN_INT64(funcentry->f_time);
+}
+
+Datum
+pg_stat_get_function_self_time(PG_FUNCTION_ARGS)
+{
+	Oid	funcid = PG_GETARG_OID(0);
+	PgStat_StatFuncEntry *funcentry;
+
+	if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
+		PG_RETURN_NULL();
+	PG_RETURN_INT64(funcentry->f_time_self);
+}
+
 Datum
 pg_stat_get_backend_idset(PG_FUNCTION_ARGS)
 {
@@ -401,7 +438,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		}
 		else
 		{
-			/* 
+			/*
 			 * Get one backend - locate by pid.
 			 *
 			 * We lookup the backend early, so we can return zero rows if it doesn't

src/backend/utils/fmgr/README

@@ -1,4 +1,4 @@
-$PostgreSQL: pgsql/src/backend/utils/fmgr/README,v 1.12 2008/04/21 00:26:45 tgl Exp $
+$PostgreSQL: pgsql/src/backend/utils/fmgr/README,v 1.13 2008/05/15 00:17:40 tgl Exp $
 
 Function Manager
 ================
@@ -70,6 +70,7 @@ typedef struct
     short       fn_nargs;   /* 0..FUNC_MAX_ARGS, or -1 if variable arg count */
     bool        fn_strict;  /* function is "strict" (NULL in => NULL out) */
     bool        fn_retset;  /* function returns a set (over multiple calls) */
+    unsigned char fn_stats; /* collect stats if track_functions > this */
     void       *fn_extra;   /* extra space for use by handler */
     MemoryContext fn_mcxt;  /* memory context to store fn_extra in */
     Node       *fn_expr;    /* expression parse tree for call, or NULL */
@@ -86,10 +87,11 @@ a function handler could set it to avoid making repeated lookups of its
 own when the same FmgrInfo is used repeatedly during a query.)  fn_nargs
 is the number of arguments expected by the function, fn_strict is its
 strictness flag, and fn_retset shows whether it returns a set; all of
-these values come from the function's pg_proc entry.  If the function is
-being called as part of a SQL expression, fn_expr will point to the
-expression parse tree for the function call; this can be used to extract
-parse-time knowledge about the actual arguments.
+these values come from the function's pg_proc entry.  fn_stats is also
+set up to control whether or not to track runtime statistics for calling
+this function.  If the function is being called as part of a SQL expression,
+fn_expr will point to the expression parse tree for the function call; this
+can be used to extract parse-time knowledge about the actual arguments.
 
 FmgrInfo already exists in the current code, but has fewer fields.  This
 change should be transparent at the source-code level.

src/backend/utils/fmgr/fmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.118 2008/05/12 00:00:52 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.119 2008/05/15 00:17:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,6 +21,7 @@
 #include "executor/functions.h"
 #include "miscadmin.h"
 #include "parser/parse_expr.h"
+#include "pgstat.h"
 #include "utils/builtins.h"
 #include "utils/fmgrtab.h"
 #include "utils/guc.h"
@@ -165,8 +166,7 @@ fmgr_info_cxt(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt)
 
 /*
  * This one does the actual work.  ignore_security is ordinarily false
- * but is set to true by fmgr_security_definer to avoid infinite
- * recursive lookups.
+ * but is set to true by fmgr_security_definer to avoid recursion.
  */
 static void
 fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
@@ -197,6 +197,7 @@ fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
 		finfo->fn_nargs = fbp->nargs;
 		finfo->fn_strict = fbp->strict;
 		finfo->fn_retset = fbp->retset;
+		finfo->fn_stats = TRACK_FUNC_ALL;	/* ie, never track */
 		finfo->fn_addr = fbp->func;
 		finfo->fn_oid = functionId;
 		return;
@@ -216,13 +217,23 @@ fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
 
 	/*
 	 * If it has prosecdef set, or non-null proconfig, use
-	 * fmgr_security_definer call handler.
+	 * fmgr_security_definer call handler --- unless we are being called
+	 * again by fmgr_security_definer.
+	 *
+	 * When using fmgr_security_definer, function stats tracking is always
+	 * disabled at the outer level, and instead we set the flag properly
+	 * in fmgr_security_definer's private flinfo and implement the tracking
+	 * inside fmgr_security_definer.  This loses the ability to charge the
+	 * overhead of fmgr_security_definer to the function, but gains the
+	 * ability to set the track_functions GUC as a local GUC parameter of
+	 * an interesting function and have the right things happen.
 	 */
 	if (!ignore_security &&
 		(procedureStruct->prosecdef ||
 		 !heap_attisnull(procedureTuple, Anum_pg_proc_proconfig)))
 	{
 		finfo->fn_addr = fmgr_security_definer;
+		finfo->fn_stats = TRACK_FUNC_ALL;	/* ie, never track */
 		finfo->fn_oid = functionId;
 		ReleaseSysCache(procedureTuple);
 		return;
@@ -255,18 +266,23 @@ fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
 			pfree(prosrc);
 			/* Should we check that nargs, strict, retset match the table? */
 			finfo->fn_addr = fbp->func;
+			/* note this policy is also assumed in fast path above */
+			finfo->fn_stats = TRACK_FUNC_ALL;	/* ie, never track */
 			break;
 
 		case ClanguageId:
 			fmgr_info_C_lang(functionId, finfo, procedureTuple);
+			finfo->fn_stats = TRACK_FUNC_PL;	/* ie, track if ALL */
 			break;
 
 		case SQLlanguageId:
 			finfo->fn_addr = fmgr_sql;
+			finfo->fn_stats = TRACK_FUNC_PL;	/* ie, track if ALL */
 			break;
 
 		default:
 			fmgr_info_other_lang(functionId, finfo, procedureTuple);
+			finfo->fn_stats = TRACK_FUNC_OFF;	/* ie, track if not OFF */
 			break;
 	}
 
@@ -862,6 +878,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 	Oid			save_userid;
 	bool		save_secdefcxt;
 	volatile int save_nestlevel;
+	PgStat_FunctionCallUsage fcusage;
 
 	if (!fcinfo->flinfo->fn_extra)
 	{
@@ -934,7 +951,19 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo = &fcache->flinfo;
 
+		/* See notes in fmgr_info_cxt_security */
+		pgstat_init_function_usage(fcinfo, &fcusage);
+
 		result = FunctionCallInvoke(fcinfo);
+
+		/*
+		 * We could be calling either a regular or a set-returning function,
+		 * so we have to test to see what finalize flag to use.
+		 */
+		pgstat_end_function_usage(&fcusage,
+								  (fcinfo->resultinfo == NULL ||
+								   !IsA(fcinfo->resultinfo, ReturnSetInfo) ||
+								   ((ReturnSetInfo *) fcinfo->resultinfo)->isDone != ExprMultipleResult));
 	}
 	PG_CATCH();
 	{
@@ -2089,7 +2118,7 @@ float4
 DatumGetFloat4(Datum X)
 {
 	union {
-		int32	value; 
+		int32	value;
 		float4	retval;
 	} myunion;
 

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.453 2008/05/12 08:35:05 mha Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.454 2008/05/15 00:17:40 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -169,7 +169,6 @@ static char *config_enum_get_options(struct config_enum *record,
 									 const char *prefix, const char *suffix);
 
 
-
 /*
  * Options for enum values defined in this module.
  */
@@ -241,6 +240,13 @@ static const struct config_enum_entry syslog_facility_options[] = {
 };
 #endif
 
+static const struct config_enum_entry track_function_options[] = {
+	{"none", TRACK_FUNC_OFF},
+	{"pl", TRACK_FUNC_PL},
+	{"all", TRACK_FUNC_ALL},
+	{NULL, 0}
+};
+
 static const struct config_enum_entry xmlbinary_options[] = {
 	{"base64", XMLBINARY_BASE64},
 	{"hex", XMLBINARY_HEX},
@@ -2524,6 +2530,15 @@ static struct config_enum ConfigureNamesEnum[] =
 		assign_session_replication_role, NULL
 	},
 
+	{
+		{"track_functions", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects function-level statistics on database activity."),
+			gettext_noop("Valid values are: NONE, PL, and ALL.")
+		},
+		&pgstat_track_functions,
+		TRACK_FUNC_OFF, track_function_options, NULL, NULL
+	},
+
 	{
 		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
 			gettext_noop("Selects the method used for forcing WAL updates to disk."),

src/backend/utils/misc/postgresql.conf.sample

@@ -363,6 +363,7 @@
 
 #track_activities = on
 #track_counts = on
+#track_functions = none			# none, pl, all
 #update_process_title = on